Stereoregularity of poly(alkyl α‐chloroacrylates) and mechanism of isotactic polymerization

Abstract

Abstract The catalytic activity of the complexes prepared by the reaction of Grignard reagents with ketones, esters, and an epoxide as polymerization catalysts of methyl and ethyl α‐chloroacrylates was investigated. The modifiers which gave isotactic polymers were α,β‐unsaturated ketones such as benzalacetophenone, benzalacetone, dibenzalacetone, mesityl oxide, and methyl vinyl ketone, and α,β‐unsaturated esters such as ethyl cinnamate, ethyl crotonate, and methyl acrylate. Catalysts with butyl ethyl ketone, propiophenone, and propylene oxide as modifiers produced atactic polymers but no isotactic polymers. It was revealed that the complex catalysts having a structure CCOMgX (X is halogen) gave isotactic polymers. The mechanism of isotactic polymerization was discussed. In addition, for radical polymerization of ethyl α‐chloroacrylate, enthalpy and entropy differences between isotactic and syndiotactic additions were calculated to give Δ H i * − Δ H s * = 910 cal/mole and Δ S i * − Δ S s * = 0.82 eu.